This invention relates generally to photolithography and more particularly to resist additives which improve the resist speed and the adhesion of the resist to the substrate surfaces encountered in the manufacture of integrated circuits.
In the manufacture of integrated circuits, resist processes are used to form patterns on the surface of the semiconductor substrate so that selected portions of the substrate can be treated. Such treatments include various etching, deposition and diffusion processes which are well known in the art of semiconductor component manufacture. The resist processes employ radiation sensitive polymer compositions which are coated onto the substrate surface and then exposed patternwise to light or other suitable electromagnetic radiation such as x-rays, gamma rays and electrons. The exposed resist layer is then developed to remove the soluble portions by treating the layer with a solvent. The portions of the substrate surface from which the resist has been removed can then be treated. One problem that occurs when the treatment is an etching process is undue enlargement of the pattern or undercutting which is the result of insufficient adhesion of the resist at the edges of the pattern. As semiconductor technology advances, the dimensions of the pattern geometry are continually decreasing so that the undercutting problem becomes more acute.
In the past, adhesion promoting coatings have been used with photoresists such as are described, for example, in Collins et al U.S. Pat. No. 3,549,368. Compounds have also been added to resist compositions to improve adhesion. We have now found a class of organic compounds which when added to resists act to improve both resist adhesion and resist speed.